Heretofore, there has been known a printing device for a corrugated paperboard sheet box making machine, wherein the printing device comprises a plurality of printing units for printing a corrugated paperboard sheet through a series of printing process, while the corrugated paperboard is conveyed from a sheet feeding device in a given conveyance direction. In this type of printing device, an actual printing position (i.e., actual position of a print pattern) on the corrugated paperboard sheet after performing the printing process by each of the printing units is likely to deviate with respect to a desired print position, in the conveyance direction. With a view to eliminating a deviation of printing position as the phenomenon that an actual print position deviates in the conveyance direction, a printing timing in each of the printing units has been adjusted according to a deviation amount of printing position. For adjusting the printing timing, it is necessary to print a pilot sheet through a series of printing processes, while conveying the pilot sheet. Generally, it is difficult to eliminate the deviation of printing position through one cycle of the printing timing adjustment. Thus, it is necessary to repeatedly measure the deviation amount of printing position by printing onto the pilot sheet, and adjust the printing timing, plural times.
The conventional method designed to actually print a pilot sheet through the printing processes and measure the deviation amount of printing position has a problem that it needs to take a lot of time and effort for preparation prior to a processing operation of the corrugated paperboard sheet box making machine, and a plurality of corrugated paperboard sheets are uneconomically consumed as pilot sheets. Moreover, the measurement of the deviation amount of printing position has to be performed every time a lot order is changed to a next one, which leads to a problem of causing deterioration in production efficiency of corrugated paperboard sheets.
With a view to improving the above problems, a corrugated paperboard sheet box making machine described in JP 2012-11600 A has been proposed. In the corrugated paperboard sheet box making machine described in JP 2012-11600 A, during a preparation stage prior to a processing operation thereof, one corrugated paperboard sheet is fed as a pilot sheet, and printed through a series of processing processes comprising a printing process and a machining process such as slotting or scoring/creasing. At least one camera is provided to image a processed portion, such as a print pattern or a slot, formed on/in the corrugated paperboard sheet. Then, an actual processing position derived from the imaged processed portion is compared with a standard or reference processing position to calculate a deviation amount of processing position. Then, a position adjustment mechanism is operable, based on the calculated deviation amount of processing position, to adjust positions of a printing plate, a slotter knife, etc., in various processing units comprising a printing unit and a machining unit such as a slotter.